/**
 * node.isEqualNode()判断两个节点对象是否相等.
 * arg  和node比较是否相等的节点.
 **/
function myFunction(x, y) {
    var item1 = document.getElementById(x).firstChild;
    var item2 = document.getElementById(y).firstChild;
    var x = document.getElementById("demo");
    x.innerHTML = item1.isEqualNode(item2);
}